PEG3 (PW1) and ZIM2 (PEG3-beta isoform) are paternally expressed in a wide variety of fetal and adult
tissues (adrenal gland, brain, heart, kidney, lung, placenta, liver, skeletal muscle, and gut) (Murphy
SK et al, 2001; van
den Veyver IB et al, 2001).
Note that mouse Zim2 is maternally expressed due to insertion of
Zim1 between Peg3 and Zim2.
However, Morcos L et al, (2011) found no evidence of
allelic expression bias in lymphoblast cell lines.